1. The Field of the Invention
The invention relates to a radio transmission system using the generalized frequency divisional multiplexing (GFDM) method.
2. The Relevant Technology
The so-called generalized GFDM system is a recent physical layer (PHY) scheme proposed to address the challenges for 5th generation cellular systems with opportunistic use of frequency spectrum and relaxed synchronization. The GFDM system provides a fast, flexible scalable and content aware physical layer scheme which at the same time is robust and reliable, while using vacant frequency bands, e.g. so-called TV white spaces. The basic GFDM system has been described in “GFDM Generalized Frequency Division Multiplexing” by Fettweis et al., IEEE VTC spring 2009.
Though the GFDM system shares some properties with well-known OFDM systems, there are significant differences. While both systems may divide an available frequency band into at least two adjoining sub-bands, the GFDM system may deploy transmission parameters individual for each of the at least two sub-bands while in OFDM the transmission parameters deployed in the sub-bands are similar or identical, i.e. uniform. Furthermore, in the OFDM system each block of symbols exhibits a unique preamble, while the GFDM system uses a common preamble for a block of symbols allocated in the at least two sub-bands.
With regard to synchronization, synchronization methods are well known and established in the various OFDM systems, while there is no synchronization procedure developed yet for GFDM which supports the efficiency of the GFDM system while exploiting the particular properties of the GFDM system. Thus the invention is directed towards improving the GFDM system.